Gate valve with seat assembly

ABSTRACT

The present invention provides a gate valve assembly having a valve body with a channel extending from a distal end to a proximal end, a gate configured to be moved from a first position to a second position, the second position being when the gate is positioned in the channel of the valve body between the distal end and the proximal end of the valve body. A seat insert is also provided to be threaded into a pocked of the valve body and a seat is configured to be positioned within the seat insert. A seal is adapted within a groove of the seat insert positioned between the valve body and the seat insert, wherein the seal is a fixed static seal providing no gaps and/or spaces between the seal insert and the valve body allowing no debris to corrupt the seals.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/276,113, filed Sep. 26, 2016 and entitled “Gate Valve With SeatAssembly”, which is a continuation of U.S. patent application Ser. No.14/311,419, filed Jun. 23, 2014 and entitled “Gate Valve with SeatAssembly”, which issued on Sep. 27, 2016 as U.S. Pat. No. 9,453,578,which claims priority to U.S. Provisional Patent Application Ser. No.61/843,701 filed on Jul. 8, 2013 and entitled “Gate Valve With SeatAssembly and Method”. The content of each of the above applications ishereby incorporated by reference.

FIELD OF THE INVENTION

The present disclosure generally relates to gate valves and inparticular to an improved seat assembly.

BACKGROUND

Gate valves that are used in the oil and gas industry typically have abody with a flow passage extending through it. The flow passageintersects a central cavity. A gate is provided to move through thecentral cavity to block the flow passage. Seal rings are used to bridgea gap between the valve body and the gate to prevent fluid from flowingaround the gate when the gate blocks the flow passage. There is a needfor an improved seat assembly to prevent leaks in the valve.

SUMMARY

A gate valve assembly is provided in one exemplary embodiment. Theassembly provides a valve body having an opening, a seat insertconfigured to be threaded it to the opening of the valve body, and aseat configured to be positioned within the seat insert.

The features and advantages of the present invention will be readilyapparent to those skilled in the art. While numerous changes may be madeby those skilled in the art, such changes are within the spirit of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the features of the present invention, a moreparticular description of the invention will be rendered by reference tospecific embodiments thereof, which is illustrated in the appendeddrawings. It is appreciated that these drawings depict only typicalembodiments of the invention and are therefore not to be consideredlimiting of its scope. The invention will be described and explainedwith additional specificity and detail with the accompanying drawings inwhich:

FIG. 1 illustrates a gate valve assembly in accordance with oneembodiment of the present invention;

FIG. 2 illustrates a seat assembly in accordance with the embodimentillustrated in FIG. 1 of the present invention;

FIG. 3 illustrates a seat assembly positioned on one side of a gatevalve assembly in accordance with one embodiment of the presentinvention;

FIG. 4 illustrates an exploded view of a seat assembly according to thepresent invention; and

FIG. 5 illustrates another view of the gate valve assembly according thepresent invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The following discussion is directed to various embodiments of theinvention. Although one or more of these embodiments may be preferred,the embodiments disclosed should not be interpreted, or otherwise used,as limiting the scope of the disclosure, including the claims. Inaddition, one skilled in the art will understand that the followingdescription has broad application, and the discussion of any embodimentis meant only to be exemplary of that embodiment, and not intended tointimate that the scope of the disclosure, including the claims, islimited to that embodiment.

FIG. 1 illustrates an improved gate valve assembly. The gate valveassembly is provided with a hand wheel 1, a packing stem 6, a bonnet 14,operating stem 19, a gate 20, a valve body 25, and a gate valve seatingassembly 100. In operation, the gate valve assembly 100 is configured sothat as the hand wheel 1 is actuated, the operating stem 19 is moved sothat the gate 20 can either close or open the channel in the valve body25. When the gate 20 is in an open position, fluid is allowed to flowthrough the channel in the valve body 25. When the gate is in a closedposition, the flow of fluid is disrupted within the channel. A gatevalve seating assembly 100 is provided between the valve body 25 and thegate 20 so that leakage of fluid from the channel when the gate isclosed may be prevented. In the preferred embodiment, a two-way gatevalve assembly is provided such that either the upstream line and thedownstream line can be attached to either side of the valve body.

Bonnet 14 is mounted to the valve body 25 by studs 16 and secured withhex nuts 27. The bonnet 14 is sealed with respect to the valve body 25by bonnet gaskets 17. Packing stem 6 provides a seal between the bonnet14 and the operating stem 19. The seal assemblies between the valve body25 and the gate valve are described in greater detail with reference toFIGS. 2-5. Attached to the bonnet 14 are also autoclave fittings 12 and15. Autoclave fitting 15 is a bleed port or a pressure release valvewhich allows an operator to release pressure with respect to the valvebody and the gasket. Autoclave fitting 12 is a grease port fitting whichallows an operator to introduce a lubricant between the bonnet 14 andthe gate 20.

Now turning to FIGS. 2 and 3, an exploded view of an improved gate valveseat assembly 100 in a preferred embodiment of the present invention isprovided. Seating assemblies are positioned as to surround channel 101and are preferably circular in construction and preferably mount intocylindrical shaped pockets. The gate valve assembly 100 is illustratedin greater detail. The gate valve assembly 100 comprises a gate 102which is used to control the flow through the flow bore channel 101 whenthe gate 102 is actuated. The assembly 100 also includes first andsecond seat inserts 104, 106 on opposing sides of the gate 102. Thefirst and second seat inserts 104 and 106 are threaded into the valvebody 108. It should be noted that the first and second seat inserts 104and 106 may be coupled to the valve body 108 by any mechanical methodssuch as press fittings or any other mechanical means. In the preferredembodiment the seat inserts 104 and 106 are threaded into the valvebody. The threads are configured so that the seat inserts may notunthread without an operator.

Annular seals 111 and 112 are positioned between the seat inserts 104and 106 and the valve body 110. These seals 111, 112 may be O-ringsand/or spring energized type seals. Any other type of mechanicallyviable seal may also be used. The seals 111, 112 may be composed ofpolymer, elastomeric, non-elastomeric, and/or metallic material or somecombination thereof and are configured to be suitable to any applicationdepending on the variability of environmental factors such as flowpressure (low/high) and temperature.

The seals 111, 112 are further adapted to be positioned within a grooveof the seat inserts 104 and 106. The seat inserts 104 and 106 arefurther configured to receive and accommodate seats 114 and 116 in acounter bore channel with seals 117 and 118 on the outside diameter ofthe seats 114 and 116. Springs 120 and 122 are also provided which arepositioned between each of the seat inserts 104 and 106 and the backface of each one of the seats 114 and 116.

Springs 120 and 122 may include several components, spacers, bushings,rings, and the like as desired to provide an initial seal force. Springs120 and 122 are preferably circular and surrounds channel 101. In thepreferred embodiment, a metallic ring seal 113 is used to provideadditional protection against any debris that may enter the spacebetween the seat insert and valve body. This allows protection of thespace between the valve body and the seat insert as well as providingprotection for the seals 111 and 112.

The arrangement of the seals and the seat inserts 104, 106 enable astatic seal between the valve body pocket and the fixed seat inserts 104and 106. The static seals 111-113 provide the benefit of allowing nogaps and/or spaces between the seat inserts 104 and 106 and the valvebody 108, thereby allowing no debris or solids to corrupt the seals111-113 which are positioned in a groove within the seat inserts 104 and106. The fixed seat inserts 104 and 106 and the seats 114 and 116 areconfigured so that they are in continuous contact with the surface ofthe gate 102 through the spring force provided by the springs 120 and122. Since the seats 114 and 116 are in continuous contact with the gatesurface, a very limited dynamic action of the seat seals 117 and 118 areprovided.

The above arrangement of the components of the valve assembly 100provides that the pressure from the flow bore channel 101 effectivelyseals all the passages by seals 111-113 and seals 117 and 118. They alsoallow for continuous contact between the seats 114 and 116 and the gate102 by the use of spring 120, thereby allowing for sealing at maximumdesigned working pressures including of the valve and in low pressuresas required. The seat inserts 104 and 106 being fixed into the valvebody 110 (pressure containing element) provides the additional benefitof protection from erosion and corrosion caused by debris and otherunwanted solids which cannot enter into the space between the seatinserts 104 and 106 and the valve body 108. As a result of using fixedseat inserts, the seals become static as provided in the preferredembodiment, the valve body assembly benefits with a longer life spancompared to using dynamic seals and non-fixed seat inserts.

The surfaces of the seats 114 and 116 are adapted to be able to sealgate 102. The surfaces may be provided with various indentations or afinished surface having a surface area that may be larger or smallerthan other surface areas of the seating assembly to effect a variableforce acting against the gate so that the sealing force that pushes thesurfaces is greater than the force that would urge the two surfacesapart.

FIG. 4 illustrates an exploded view of the seat assembly 200. The seatassembly 200 includes a seat retainer 202, a disc spring 204 positionedwithin a groove of the seat retainer 202, a trash ring 206 positionedwithin the seat retainer 202. A seat assembly 200 also includes a seatthat is configured to with within the groove of the seat retainer 202.That assembly 200 further includes high pressure/high temperature seals210 positioned between the seat retainer 202 and the valve body. Theseat 20 is also provided with at least one high pressure/hightemperature seal 212.

FIG. 5 illustrates the seat assemblies 200 and 220 positioned within avalve body when the gate is in a closed position. As illustrated in FIG.5, seat assemblies 200 and 220 are positioned on the both the upstreamand downstream portions of the valve body. As a result, the seatingmechanism used in the seat assemblies provides improved sealing on boththe upstream and downstream of the valve body. The seat retainers 202and 222 are threaded into the valve body 201. High pressure/Hightemperature seals 210 and 224 are positioned between the seat retainers202 and 222 and the valve body 201. Although high pressure/hightemperature seals are used in this embodiment, any type of seal may beused.

During operation of the gate valve, the fluid enters into the channeland the valve body pressure is automatically de-energized to thedownstream pressure and this is achieved by the valve body pressurewhich moves the seat toward the seat insert by pushing the springcreating a gap between the gate and the seat. As a result, the valvebody pressure is drained to equal to the lowest pressure of the sides.

Thus, an embodiment includes a gate valve assembly, some of which isshown in the embodiment of FIG. 3. The assembly includes a valve bodyhaving a channel extending from a distal channel portion at a distal endof the valve body to a proximal channel portion at a proximal end of thevalve body. The assembly includes a gate 101 configured to move betweenopen and closed positions, the closed position being when the gate is inthe channel. The assembly includes a first seat insert 104 and a secondseat insert in first and second pockets of the valve body and onopposing sides of the gate from one another. A first seat 114 is betweenthe first seat insert and the gate and a second seat is between thesecond seat insert and the gate. The assembly includes a static firstseal (e.g., seal 111) between the valve body and the first seat insertand a static second seal between the valve body and the second seatinsert. The assembly includes a first spring 122 directly contacting thefirst seat and the first seat insert and a second spring directlycontacting the second seat and the second seat insert. In the assembly(a)(i) the first seat has a first proximal outer diameter (e.g.,directly adjacent spring 122 and measured vertically in parallel to longaxis of gate 101) and a first lip (e.g., directly adjacent gate 101)having a first distal outer diameter, (a)(ii) the first distal outerdiameter is between the gate and the first proximal outer diameter, and(a)(iii) the first distal outer diameter is greater than the firstproximal diameter. In the assembly (b)(i) the second seat has a seconddistal outer diameter and a second lip having a second proximal outerdiameter, (b)(ii) the second proximal outer diameter is between the gateand the second distal outer diameter, and (b)(iii) the second proximalouter diameter is greater than the second distal diameter. In theassembly inner surfaces of each of the first and second seat inserts andeach of the first and second seats each at least partially form thechannel and are each configured to directly contact fluid when the fluidis traversing the channel. In the assembly the first spring isconfigured such that: (c)(i) the first spring biases the first seatagainst the gate when there is no fluid pressure in the proximal channelportion, (c)(ii) the first spring directly contacts the fluid when thereis fluid pressure in the proximal channel portion, (c)(iii) the fluidforces the first seat against the gate when there is fluid pressure inthe proximal channel portion, (c)(iv) the first spring biases the firstseat insert towards the static first seal (e.g., seal 111) and againstthe valve body when there is no fluid pressure in the proximal channelportion, and (c)(v) the first spring compresses, when fluid pressure inthe valve body exceeds fluid pressure in the proximal channel portion,to allow the first seat to move towards the first seat insert to lowerthe fluid pressure in the valve body. In the assembly the second springis configured such that: (c)(i) the second spring biases the second seatagainst the gate when there is no fluid pressure in the distal channelportion, (c)(ii) the second spring directly contacts the fluid whenthere is fluid pressure in the distal channel portion, (c)(iii) thefluid forces the second seat against the gate when there is fluidpressure in the distal channel portion, (c)(iv) the second spring biasesthe second seat insert against the valve body when there is no fluidpressure in the distal channel portion, and (c)(v) the second springcompresses, when fluid pressure in the valve body exceeds fluid pressurein the distal channel portion, to allow the second seat to move towardsthe second seat insert to lower the fluid pressure in the valve body.

In the embodiment of FIG. 3 the assembly includes a first dynamic seal(e.g., seal 118) in a first slot between the first seat and the firstseat insert and a second dynamic seal in a second slot between thesecond seat and the second seat insert.

In the embodiment of FIG. 3 the first and second springs are configuredsuch that: the first spring biases the first seat against the gate whenthere is fluid pressure in the proximal channel portion; the firstspring biases the first seat insert against the valve body when there isfluid pressure in the proximal channel portion; the second spring biasesthe second seat against the gate when there is fluid pressure in thedistal channel portion; and the second spring biases the second seatinsert against the valve body when there is fluid pressure in the distalchannel portion.

In the embodiment of FIG. 3 the first seat includes a first sidewall(e.g., directly adjacent spring 122 and extending vertically) thatcouples to the inner surface (extending horizontally) of the first seatand the second seat includes a second sidewall that couples to the innersurface of the second seat. The fluid forces the first seat against thegate, when there is fluid pressure in the proximal channel portion, bydirectly contacting the first sidewall; and the fluid forces the secondseat against the gate, when there is fluid pressure in the distalchannel portion, by directly contacting the second sidewall.

While it is apparent that the invention disclosed herein is wellcalculated to fulfill the objects stated above, it will be appreciatedthat numerous modifications and embodiments may be devised by thoseskilled in the art.

What is claimed is:
 1. A gate valve assembly comprising: a valve bodyhaving a channel extending from a distal channel portion at a distal endof the valve body to a proximal channel portion at a proximal end of thevalve body; a gate configured to move between open and closed positions,the closed position being when the gate is in the channel; first andsecond seat inserts screwed into first and second pockets of the valvebody and on opposing sides of the gate from one another; a metal firstseat that directly contacts the first seat insert and the gate and ametal second seat that directly contacts the second seat insert and thegate; a static first seal that directly contacts the valve body and thefirst seat insert and a static second seal that directly contacts thevalve body and the second seat insert; an additional static first sealthat directly contacts the valve body and the first seat insert, and anadditional static second seal that directly contacts the valve body andthe second seat insert; a first spring directly contacting the firstseat and the first seat insert and a second spring directly contactingthe second seat and the second seat insert; a first dynamic seal atleast partially included in a first slot and directly contacting thefirst seat and the first seat insert, the first slot existing betweenthe first seat and the first seat insert; a second dynamic seal at leastpartially included in a second slot and directly contacting the secondseat and the second seat insert, the second slot existing between thesecond seat and the second seat insert; wherein (a)(i) the first seathas a first proximal outer diameter and a first lip having a firstdistal outer diameter, (a)(ii) the first distal outer diameter isbetween the gate and the first proximal outer diameter, and (a)(iii) thefirst distal outer diameter is greater than the first proximal diameter;wherein (b)(i) the second seat has a second distal outer diameter and asecond lip having a second proximal outer diameter, (b)(ii) the secondproximal outer diameter is between the gate and the second distal outerdiameter, and (b)(iii) the second proximal outer diameter is greaterthan the second distal diameter; wherein inner surfaces of each of thefirst and second seat inserts and each of the first and second seatseach at least partially form the channel and are each configured todirectly contact fluid when the fluid is traversing the channel; whereinthe first spring is configured such that: (c)(i) the first spring biasesthe first seat against the gate when there is no fluid pressure in theproximal channel portion, (c)(ii) the first spring directly contacts thefluid when there is fluid pressure in the proximal channel portion,(c)(iii) the fluid forces the first seat against the gate when there isfluid pressure in the proximal channel portion, (c)(iv) the first springbiases the first seat insert towards the static first seal and theadditional static first seal and against the valve body when there is nofluid pressure in the proximal channel portion, and (c)(v) the firstspring compresses, when fluid pressure in the valve body exceeds fluidpressure in the proximal channel portion, to allow the first seat tomove towards the first seat insert to lower the fluid pressure in thevalve body; wherein the second spring is configured such that: (c)(i)the second spring biases the second seat against the gate when there isno fluid pressure in the distal channel portion, (c)(ii) the secondspring directly contacts the fluid when there is fluid pressure in thedistal channel portion, (c)(iii) the fluid forces the second seatagainst the gate when there is fluid pressure in the distal channelportion, and (c)(iv) the second spring biases the second seat insertagainst the valve body when there is no fluid pressure in the distalchannel portion; wherein the first seat is configured to prevent thefirst seat insert from directly contacting the gate; wherein the firstseat and the gate are configured to form a metal-to-metal seal; whereinthe metal-to-metal seal has an uppermost point of contact between thegate and the first seat and a lowermost point of contact between thegate and the first seat; wherein the metal-to-metal seal is configuredso, between the uppermost point of contact and the lowermost point ofcontact, only metal materials of the gate and the first seat directlycontact each other.
 2. The assembly of claim 1, wherein the first andsecond springs are configured such that: the first spring biases thefirst seat against the gate when there is fluid pressure in the proximalchannel portion; the first spring biases the first seat insert againstthe valve body when there is fluid pressure in the proximal channelportion; the second spring biases the second seat against the gate whenthere is fluid pressure in the distal channel portion; and the secondspring biases the second seat insert against the valve body when thereis fluid pressure in the distal channel portion.
 3. The assembly ofclaim 1, wherein: the first seat includes a first sidewall that extendsfrom the inner surface of the first seat; the second seat includes asecond sidewall that extends from the inner surface of the second seat;the fluid forces an additional first sidewall of the first seat directlyagainst the gate to form the metal-to-metal seal, when there is fluidpressure in the proximal channel portion, in response to the fluiddirectly contacting the first sidewall; the fluid forces the second seatagainst the gate, when there is fluid pressure in the distal channelportion, by directly contacting the second sidewall; and the first seatincludes a monolithic metal portion that extends from the first sidewallto the additional first sidewall.
 4. The assembly of claim 1, wherein:an axis intersects the static first seal, the first seat insert, thefirst seat, and the gate when the gate is closed; the axis is parallelto a long axis of the channel; an additional axis, which is not parallelto the long axis, intersects both the static first seal and theadditional static first seal.
 5. The assembly of claim 4 comprising:another static first seal between the valve body and the first seatinsert; wherein the additional axis does not intersect the anotherstatic first seal.
 6. The assembly of claim 1 comprising another staticfirst seal between the valve body and the first seat insert.
 7. Theassembly of claim 6 wherein: the static first seal and the additionalstatic first seal are both spring energized seals; the static first sealand the additional static first seal both include metal; and the anotherstatic first seal includes metal.
 8. The assembly of claim 6, wherein:the another static first seal is between the static first seal and aplurality of threads; the first seat insert is screwed into the firstpocket of the valve body via the threads; the first spring surrounds thechannel; the static first seal is included in a channel located in aface of the first seat insert; the additional static first seal isincluded in an additional channel located in the face of the first seatinsert; and the first dynamic seal is located between the first springand the gate.
 9. The assembly of claim 1, wherein: the first slotincludes a channel having a bottom and sidewalls that connect to eachother via the bottom; the bottom and the sidewalls are all exterior wallportions of the first seat; at least a portion of the first dynamic sealsimultaneously and directly contacts the bottom and the sidewalls.
 10. Agate valve assembly comprising: a valve body having a channel extendingfrom a distal channel portion at a distal end of the valve body to aproximal channel portion at a proximal end of the valve body; a gateconfigured to move between open and closed positions, the closedposition being when the gate is in the channel; first and second seatinserts included in first and second pockets of the valve body and onopposing sides of the gate from one another; a metal first seat betweenthe first seat insert and the gate and a metal second seat between thesecond seat insert and the gate; a static first seal between the valvebody and the first seat insert and a static second seal between thevalve body and the second seat insert; a first spring between the firstseat and the first seat insert and a second spring between the secondseat and the second seat insert; a first dynamic seal at least partiallyincluded in a first slot, the first slot existing between the first seatand the first seat insert; a second dynamic seal at least partiallyincluded in a second slot, the second slot existing between the secondseat and the second seat insert; wherein inner surfaces of each of thefirst and second seat inserts and each of the first and second seatseach at least partially form the channel and are each configured todirectly contact fluid when the fluid is traversing the channel; whereinthe assembly is configured such that: (i) the first spring biases thefirst seat against the gate when there is no fluid pressure in theproximal channel portion, (ii) the first spring directly contacts thefluid when there is fluid pressure in the proximal channel portion, and(iii) the first spring biases the first seat insert towards the staticfirst seal and the valve body when there is no fluid pressure in theproximal channel portion; wherein the assembly is configured such that:(i) the second spring biases the second seat against the gate when thereis no fluid pressure in the distal channel portion, (ii) the secondspring directly contacts the fluid when there is fluid pressure in thedistal channel portion, and (iii) the second spring biases the secondseat insert towards the valve body when there is no fluid pressure inthe distal channel portion; wherein the first seat is between the firstseat insert and the gate; wherein the first seat and the gate areconfigured to form a metal-to-metal seal; wherein the metal-to-metalseal has an uppermost point of contact between the gate and the firstseat and a lowermost point of contact between the gate and the firstseat; wherein the lowermost point of contact is between the uppermostpoint of contact and the channel; wherein the metal-to-metal seal isconfigured so, between the uppermost point of contact and the lowermostpoint of contact, only metal materials of the gate and the first seatare in direct contact with each other.
 11. The assembly of claim 10,wherein the first and second springs are configured such that: the firstspring biases the first seat against the gate when there is fluidpressure in the proximal channel portion; the first spring biases thefirst seat insert towards the valve body when there is fluid pressure inthe proximal channel portion; the second spring biases the second seatagainst the gate when there is fluid pressure in the distal channelportion; and the second spring biases the second seat insert towards thevalve body when there is fluid pressure in the distal channel portion.12. The assembly of claim 10, wherein: the first seat includes a firstsidewall orthogonal to the inner surface of the first seat; the secondseat includes a second sidewall orthogonal to the inner surface of thesecond seat; the fluid forces the first seat against the gate, whenthere is fluid pressure in the proximal channel portion, by directlycontacting the first sidewall; and the fluid forces the second seatagainst the gate, when there is fluid pressure in the distal channelportion, by directly contacting the second sidewall.
 13. The assembly ofclaim 10, wherein: the assembly is configured such that the fluid is todirectly contact a face of the first seat insert to force the first seatinsert towards a vertical face of the first pocket of the valve bodywhen there is fluid pressure in the proximal channel portion; the faceof the first seat insert extends from the inner surface of the firstseat insert.
 14. The assembly of claim 10, wherein: the assembly isconfigured such that the fluid is to directly contact a face of thefirst seat insert to force the first seat insert towards a non-threadedface of the first pocket of the valve body when there is fluid pressurein the proximal channel portion; the face of the first seat insertextends from the inner surface of the first seat insert.
 15. Theassembly of claim 10, wherein the assembly is configured such that: thefluid forces the first seat against the gate when there is fluidpressure in the proximal channel portion, and the first springcompresses, when fluid pressure in the valve body exceeds fluid pressurein the proximal channel portion, to allow the first seat to move towardsthe first seat insert.
 16. A gate valve assembly comprising: a valvebody having a channel extending from a distal channel portion at adistal end of the valve body to a proximal channel portion at a proximalend of the valve body; a gate configured to move between open and closedpositions, the closed position being when the gate is in the channel;first and second seat inserts in first and second pockets of the valvebody and on opposing sides of the gate from one another; a metal firstseat between the first seat insert and the gate and a metal second seatbetween the second seat insert and the gate; a first spring between thefirst seat and the first seat insert and a second spring between thesecond seat and the second seat insert; a first dynamic seal at leastpartially between the first seat and the first seat insert and a seconddynamic seal at least partially between the second seat and the secondseat insert; wherein inner surfaces of each of the first and second seatinserts and each of the first and second seats each at least partiallyform the channel and are each configured to directly contact fluid whenthe fluid is traversing the channel; wherein in a first orientation theassembly is configured so: (i) the first spring biases the first seatagainst the gate, (ii) the first spring directly contacts the fluid whenthe fluid is traversing the channel, and (iii) the first spring biasesthe first seat insert towards the valve body; wherein in a secondorientation the assembly is configured so: (i) the second spring biasesthe second seat against the gate, (ii) the second spring directlycontacts the fluid when the fluid is traversing the channel, and (iii)the second spring biases the second seat insert towards the valve body;wherein the first seat is between the first seat insert and the gate;wherein the first seat and the gate are configured to form ametal-to-metal seal; wherein the metal-to-metal seal has a first pointof contact between the gate and the first seat and a second point ofcontact between the gate and the first seat; wherein the second point ofcontact is between the first point of contact and the channel; whereinthe metal-to-metal seal is configured so, between the first point ofcontact and the second point of contact, only metal materials of thegate and the first seat are in direct contact with each other.
 17. Theassembly of claim 16, wherein: the first seat includes a first sidewallorthogonal to the inner surface of the first seat; the second seatincludes a second sidewall orthogonal to the inner surface of the secondseat; the fluid forces the first seat against the gate, when theassembly is in the first orientation and when the fluid is traversingthe channel, by the fluid directly contacting the first sidewall; andthe fluid forces the second seat against the gate, when the assembly isin the second orientation and when the fluid is traversing the channel,by directly contacting the second sidewall.
 18. The assembly of claim16, wherein: the fluid is to force the first seat insert towards anon-threaded face of the first pocket of the valve body when theassembly is arranged in the first orientation and when the fluid istraversing the channel; the first spring is removably coupled to thefirst seat insert.
 19. The assembly of claim 16, wherein the fluid is toforce the first seat against the gate when the assembly is arranged inthe first orientation and when the fluid is traversing the channel. 20.The assembly of claim 16 comprising a static first seal between thevalve body and the first seat insert and a static second seal betweenthe valve body and the second seat insert.